Combination propeller and diffuser inlet assembly



H. H. CURRY 2,620,122 COMBINATION PROPELLER AND DIFFUSER INLET ASSEMBLY Dec. 2, 1952 Filed Oct. 9, 1945 bfez'man EC Patented Dec. 2, 1952 "UNITED PAT N OFFICE INLET ASSEMBLY Herman H.'-Curry, United StatesLCdaSt Guard uppuimutncamber9.194 5, ser amo'. 321,396 16: Claims.' (of. 230-45) (Granted under This invention relates to jetpropulsion for aircraft, flying bombs,-etc., wherein a high efliciency of operation is maintained by taking advantage of intermittent combustion of stratified charges of air and combustible mixture, operating at resonant speeds with or without a snap or vibratory-reed type of check valve at the inlets to the combustion chambers, which maybe arranged annularly about the axis of thepower unit. Novel arrangements of compressor and turbine blading, together with a propeller are-disclosed herein;

'An object of this inventionis "1'10 providethe combination of an air diffuser havingan inlet of maximumarea in accordance with reasonable design standards, and means includinga-propeller mounted in advance ofthe inlet but'bei-ng of a predetermined diameter greater than the diameter of the diffuser inletior increasing the effective intake ability of the diffuser. The'spacing of theinlet 'andpropeller is such that the normal propeller slipstream contraction causes a mass flow of air to pass into the "diffuser'inlet, larger thanthat which-wouldijbe accepted-by the diffuser in the-absence of the propeller.- In "this way the propeller-inlet relationship createsa 'situation wher the prqpfiller wdiscgarea forms a virtual inlet orifice for the diffuser, that is of an area greater than the actualinlet of thediifu'ser.

Other objects will becomeapparent infollo'wing the description of the illustrated forms of the invention:

In the drawing:

Fig. 1 is a fragmentary elevational view of a jet type engine with portions shown in section; and

Fig. 2 is a fragmentary elevational view of a modified form of the invention.

In Fig. 1 there is a streamlined body consisting of a casing I having a rotor I2 axially mounted therein, a rotor including blading I4 and other components essential to a jet engine but which are not necessary to an understanding of the invention. A spinner I6 either including or actuated through reduction gearing. is disposed at the forward end of the rotor I2 and is located at least in part in advance of the casing. Propeller 20 is suitably connected with the spinner I6 and is mounted on the part of the spinner that is forward of the casing I0.

A diffuser 22 is formed between the casing inner surface and rotor I2 in order to receive air for engine operation. Even though the inlet 24 of the diffuser may be made as large in area as possible, while remaining within the realm of sound design principles, it would be beneficial to inthe 'act of March 3, 1883,1as amended" April 30, 1928; 370 O. 6:. 7157.

crease the capability 'ofthe diffuser '22 together with its inlet- 24 to receive a greater mass flow-of air per unit areathanis possible with ordinary V diffusers, turbo-prop arrangements or other combinations of propeller-jetengines. This is accomplished by takingadvantage of the propeller slipstream. and specifically the fact that the slipstream contracts a short distance behind its propeller. By making the propeller slightly larger in diameter than the diameter of-the inlet 24, the slipstream at its maximumlcontraction plane may be-made to enter directly-into the inlet 24. The result is that the virtual larea of the diffuser inlet 24 is increased to the propeller-discarea and hence, a greater mass flow of entry into the diffuser Tfor a given forward speed is realized.

The propeller size; its distance from the inlet 24 and the typeof diffuser and inlet are related so that-achange. in design of one factor usually requires changes intheother;

Operating on asimilar principle is the embodiment of Fig. '2, wh'erelthecasing '30 has its axially arranged rotor .32 provided with a propeller 34 I mounted for rotation in advance of the diffuser inlet 36. This form oftheinvention distinguishes from thatofjFig. 1' principally in the presence-of the housing 38 held'by' suitable means in concentric spaced relationship withth'e casing 30 to define anair passage whose frontal entrance 42, usually annular, opens forwardly to receive slipstream air from the propeller 34. Not only will the air in the passage 40 inherently function to cool the casing 30, but also, the air may be used to develop additional thrust, for cabin heating and for sundry purposes. From inspection of the flow lines, it is observed that the contracted slipstream in part enters passage 40 and in part passes into the diffuser inlet 36.

Obviously, many other modifications in the form and arrangement of the several parts of the device shown herein may be made without departing from the spirit and scope of this in vention as defined in the appended claims,

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. In a jet propulsion device, a streamlined body having a rotor axially mounted therein and an inlet with an inlet area equal to the maximum forward projected area of the body, a propeller driven by said rotor and disposed in advance of said body, said propeller having a diameter greater than said inlet and the propeller disc area forming a virtual inlet of greater diameter than the inlet of said body, and the propeller while in rotation having a slipstream that converges to a minimum diameter at said body inlet and substantially entirely enters said inlet.

2. In a jet propulsion apparatus arranged to induct and direct rearwardly a mass of air for reaction propulsion while advancing, said apparatus including a casing having a diffuser with an inlet of maximum design area, a propeller having a slipstream during rotation coaxial with said inlet, said propeller being spaced ahead of the plane of said inlet a predetermined distance so that the propeller disc area forms a virtual inlet opening of greater area than said first-mentioned inlet, and due to the contraction of the slipstream of the propeller at least the major portion of the slipstream enters the diffuser inlet to increase the mass flow through said diffuser.

3. In a jet propulsion device, a casing provided with an air diffuser having a, frontal inlet of maximum design area, means for increasing the mass flow acceptance of said diffuser inlet, said means including a propeller mounted for rotation in advance of said casing andin front of said inlet, said propeller having an axis of rotation coincident with the longitudinal axis of said casing and said propeller While in rotation having a slipstream which has an area after usual contraction behind the propeller substantially equal to the area of said frontal inlet so that the propeller disc area forms a virtual inlet for the diffuser greater in area than the area of the actual inlet of said diffuser.

4. The combination of claim 3 and; a housing concentrically arranged with respect to said casing and spaced from the exterior thereof to define an air passage, said passage having a forwardly opening entrance, and said entrance being located in alignment with the peripheral portion of the contracted part of the propeller slipstream.

5. In a jet propulsion apparatus which includes a casing provided with an air diffuser having an inlet, means for increasing the mass flow of air passing through said inlet at a given forward speed of the jet propulsion apparatus, said means consisting of a propeller mounted for rotation in advance of said inlet and of a diameter greater than the diameter of said inlet, said propeller diameter being only slightly larger than the inlet diameter, and the relationship of the spacing between the propeller and inlet together with said diameters being such that the propeller slipstream contraction area is substantially equal to the area of said inlet at the point of entry of said slipstream into said inlet.

6. In a jet propulsion apparatus which includes a casing provided with an air difiuser having an inlet, means providing a virtual inlet for said diffuser inlet which is greater in area than said diffuser inlet to thereby increase the capability of said difiuser inlet to accept air flow, said means consisting of apropeller disposed in advance of said diffuser inlet and having a, disc area greater than the area of said diffuser inlet, and the propeller diameter with respect to the diffuser inlet diameter being such that the propeller slipstream contraction area at the plane of entry into said diffuser inlet is substantially equal to the area of the diffuser inlet.

HERMAN H. CURRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name l Date 7 311,106 Corey Jan. 20, 1885 1,319,752 Brown Oct..28, 1919 2,010,020 Holzwarth Aug. 6,1935 2,174,266 Jackson et a1 Sept. 26, 193.9 2,287,822 Odor et al June 30, 1942 2,326,072 Seippel Aug. 3, 1943 2,334,561 Kopplin -1 Nov. 16, 1943 2,404,767 Heppner -1 July 23, 1946 2,405,785 Goddard Aug. 13, 1946 2,407,164 Kimball Sept. 3, 1946 2,427,845 Forsyth Sept. 23, 1947 2,435,236 Redding' Feb. 3, 1948 2,454,310 de Ganahl Nov. 23, 1948 2,454,738 Hawthorne 'Nov. 23, 1948 2,506,581 Cowles 1.. May 9, 1950 FOREIGN PATENTS Number Country Date 174,179 Great Britain Jan. 19, 1922 

